# Build cloudflare-ddns-update into a container which runs it through a cron job every 15m.
#
# Build locally:
#   $ docker build .
#
# Test locally:
#   $ docker run \
#       -e "CF_DDNS_AUTH_TOKEN=…" \
#       -e "CF_DDNS_ZONE_ID=…" \
#       -e "CF_DDNS_RECORD_NAME=…" \
#       <hash>
#
#   Stop by checking container ID in `docker ps -a` and running `docker stop <id>`.
#
# Tag:
#   $ docker build -t jakewharton/cloudflare-ddns-update:<version> .
#
# Release:
#   $ docker push jakewharton/cloudflare-ddns-update:<version>
#
# Content dervied in part from:
# - https://stackoverflow.com/a/46220104/132047
# - https://stackoverflow.com/a/47960145/132047
# - https://alexbrand.dev/post/how-to-package-rust-applications-into-minimal-docker-containers/
# - https://roboslang.blog/post/2017-12-06-cron-docker/

# Cross-compile the app for musl to create a statically-linked binary.
FROM clux/muslrust:1.40.0-stable AS build
WORKDIR /
RUN USER=root cargo new app
WORKDIR /app
COPY Cargo.toml Cargo.lock ./
COPY src ./src
RUN cargo build --release

# Build a container which runs the binary with cron.
FROM alpine:3.6
RUN apk update && apk add ca-certificates && rm -rf /var/cache/apk/*
WORKDIR /app
COPY docker/cron_cli.sh docker/cron_cmd.sh ./
COPY docker/crontab /etc/crontabs/root
COPY --from=build /app/target/x86_64-unknown-linux-musl/release/cloudflare-ddns-update ./
ENTRYPOINT ["/app/cron_cmd.sh"]